This is a single center, single arm, open-label Phase I study to establish the safety of interstitial laser thermal therapy (ILTT) in patients with a single site of low grade (Gleason <7) prostate cancer who have not yet received treatment for their cancer. No control group will be utilized and all patients will receive laser thermal therapy. The patient will undergo multimode MRI to determine if a single site of prostate cancer can be localized by this technique and to localize the tumor in 3 dimensions within the prostate. A multicore (12 + cores) mapping transrectal ultrasound guided biopsy of the prostate would then confirm that no other sites of cancer exist.